JPS63254833A - Method and system for radio channel switching for mobile communication - Google Patents

Abstract

PURPOSE:To eliminate noise due to communication interruption and intermodulation by providing a means sending/receiving a signal to/from a mobile radio equipment through channel changeover so as to switch the channel so that the communication quality with a radio base is always at a constant value or over. CONSTITUTION:Transmission/reception circuits 61, 63 having a transmission/reception mixer and switching means 64, 65, 67 including a synthesizer 55 transmitting/receiving two channel signals through changeover while adding two frequencies are mounted on a mobile radio equipment. If the quality is deteriorated below the prescribed quality due to moving during the communication with a base station through the 1st channel, the communication is started with other base station acquiring the best quality through a 2nd channel. Prior to the start, a channel changeover means 64 switches the 1st and 2nd channels alternately for the communication, and after the communication quality is confirmed to be a prescribed value or over through the 2nd channel, then the communication is consecutive only by the 2nd channel. As a result, noise due to communication interruption and intermodulation attended with the channel changeover is excluded and the communication quality of a prescribed value is used for mobile communication.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and system for switching wireless communication channels for mobile communication. More specifically,
In mobile communication using a small zone configuration, mobile communication during communication! When a Fl terminal moves and the communication quality with the fixed wireless station it is communicating with deteriorates, it may open a new communication channel with another fixed wireless station that is nearby and satisfies the communication quality. The present invention relates to a so-called communication channel switching method and system for setting and canceling a previous communication channel.

[Prior Art] This type of conventional technology is employed, for example, in the car telephone system of NTT (Nippon Telegraph and Telephone Corporation), which is currently in commercial service. In this case, the mobile radio installed in the car moves away from the wireless base station of the other party as the car moves, and for example, when the distance is 5 to 7 candy or more from the wireless base station, the received electric field value of the radio wave decreases. Therefore, deterioration of call quality occurs. Therefore, in a small zone configuration, wireless base stations are installed within the service area at intervals of 10 to 12 touch points from each other, and therefore, in the above case, there is always another wireless base station near the current location of the vehicle (within 5 to 6 KIn). exists, and a separate radio channel is used between the new radio base station and the mobile radio to continue the call. In the NTT system, a radio line control station is installed to control a large number of radio base stations and mobile radios, and the radio line control station controls the setting and cancellation of calls on radio lines. When quality deterioration occurs, multiple wireless base stations around the mobile wireless device receive the radio waves transmitted by the mobile wireless device, and a specific wireless base station among these receives a new wireless channel between the mobile wireless device and the mobile wireless device. When it is determined that the desired call quality can be maintained by setting the new channel, the mobile radio sets the new channel between the mobile radio and the radio base station.

FIG. 8 shows a conceptual diagram of the configuration of a conventional system that operates as described above, and will be described using this diagram.

In Figure 8, the radius surrounded by four circles is 5 to 7 KIl.
Each of the zones 14A, 14B, 14G, and 14D of about t is the service area of the car telephone, and the mobile radio device 15 currently installed in the car is the radio base station 1 in the zone 14A.
Assume that communication is in progress with 3A.

Since the automobile is traveling from zone 14A to zone 14C, the relative distance between radio base station 13A and mobile radio 15 is increasing.

Assuming that the communication is continuing and the car moves from zone 14A to zone 14C, the distance between the wireless base station 13A and the mobile wireless device 15 will be 5 to 7 km or more, and the input electric field value of mutually received radio waves will be The transmission quality decreases, leading to a drop below a certain level of transmission quality. This state of quality deterioration is constantly monitored by the radio network control station 12, and when the quality deteriorates below a certain standard, radio base stations 138, 130 and 13D in the vicinity of the radio base station 13A are Station 13
A request is made to measure the quality of the radio channel (assumed to be channel CH1) in use between A and the mobile radio 15. The radio base stations 13B, 13C, and 13D that have received this request each tune their own radio channel search receivers (not shown) to channels C1-11 to receive the signal, and the state is determined by radio channel control. Report to station 12. The radio network control station 12 that received this report receives the received input electric field EB of the radio base stations 13B, 13C, and 130.

Compare the values of EC1 and ED, Eo>E,,E. >E
, and when the EC confirms that a certain level of quality is ensured from the perspective of transmission quality, the radio network control station 12 considers that the zone has moved from zone 14A to zone 14C, and uses it in zone 14A. radio channel C
A procedure for disconnecting HI and using an unused channel (assuming channel CHIO) among the radio channels available at the radio base station 13G in the zone 14C, ie, switching the busy channel, is started.

Below are the references: Old and other "Car phone radio line control" Nippon Telegraph, Telephone and Telecommunications Research Institute Research and Practical Application Report VO1, 26,
This will be explained with reference to No. 7 18851.

(1) The channel switching signal is transmitted between the radio network control station] 2 and each radio base station 13 using a control line included in each transmission path 16, and between each radio base station 13 and mobile radio device 15. is a wireless communication channel.

(2) The channel switching signal is sent from, for example, the wireless base station 13A with which the mobile heat I! was previously communicating. The radio continuity test tone is sent to the mobile radio device 15 from, for example, the radio base station 13C that is to be newly switched.

(3) When the mobile radio 15 cannot receive the radio continuity test tone, it returns to the old communication channel set with the radio base station 13A and continues the communication.

The above (1) to (3) are the channel switching methods currently used by NTT during a call, but as is clear from these explanations, the caller, i.e., the automated telephone call user, may experience the following noises during a call. It will be mixed in. That is, (a) the control signal for switching according to (1) above (in this case, a 300 bit/sec digital signal) is received in a form that is inserted into the chitnel during the call after the other party's signal is disconnected; Since it appears in the output of the machine, it mixes into the call as an audible sound of about 300 Hz, and the call is interrupted during this time.

(b) During the call test described in (2) above, there is no noise or there is no sound, and during this period, the other party's voice is not transmitted to the other party, and neither is one's own voice to the other party (call disconnection).

The duration of call interruption due to (a) and (b) above is 0.7
It is said to be ~0.8 seconds. On the other hand, the radio network control station 12
Then, to the radio base station 13C, for example, the channel C)-11 is transmitted to the mobile radio station 15 through the transmission path 16G between the two.
0 to start a call. Since this instruction is also carried out at the same time as the continuity test described above, at this moment the wireless base station 13A ends communication with the mobile wireless device 15, and the wireless base station 13C instead Start communication with 15. The radio network control station 12 also provides a communication path switch S in the exchange 11 for connecting each radio base station 13 to the telephone network 10 for communication@FM11 of the telephone network 10.
A request is made to switch W from the wireless base station 13A to 130. In other words, when the communication path switch SW in FIG.
-4 switch is turned off (shown as a blank triangle), C-
4 Turn on the switch (indicated by a black triangle).

Through the above operations, the mobile radio P315 can be used inside the car to continue talking to any telephone within the telephone network 10, no matter where the car moves in zones 14A, 14B, 14C, or 14D. .

In this way, the user (caller) is given a technical guarantee that he or she can make a call anytime and anywhere within the service area while the car is in motion. That service is good.

[Problems to be Solved by the Invention] However, in the above-mentioned call channel switching method implemented by NTT, calls are temporarily disconnected (for 0.7 to 0.8 seconds) when switching wireless channels. In addition, there is a drawback that part of the control signal (300 bits/sec) other than the call signal may be mixed in. If there is a temporary interruption in the call line or noise, it is not a big problem because it can be compensated for by listening again when the content of the call is voice, but it is not a big problem. When a facsimile terminal is installed and used for sending and receiving, if the channel is changed during operation, for example, for a 1-minute facsimile, a black line (or white line) will appear on the 0.8/60 part of the page, resulting in poor reception image quality. The disadvantage was that it deteriorated significantly. In the case of data communication, for example, 120
With a 0 baud data signal, approximately 1000 bits of the signal are lost, so procedures such as retransmission are required.

In order to eliminate annoying IG noise, there are methods such as silencing the channel during channel switching or using out-of-band signals, but although the purpose of eliminating annoying noise can be achieved, it does not reduce the amount of time the line is disconnected. still exists, and the problem remains that it is completely ineffective in eliminating the negative effects on facsimile and data signals.

[Means for Solving the Problems] A wireless reception circuit includes a plurality of wireless base stations each having a wireless transceiver and a reception mixer that communicates while moving within a hot service area covered by the plurality of wireless base stations. and,
A wireless transmitting circuit having a transmitting mixer, a switching receiving means including a synthesizer capable of applying two frequencies to a receiving mixer of the wireless receiving circuit to switch and receive signals of two channels, and a transmitting circuit of the wireless transmitting circuit. A system is constructed that includes a mobile radio including switching transmission means including a synthesizer that can switch and transmit signals of two channels by applying two frequencies to a mixer.

[Operation] One radio base station and mobile radio device are connected to one channel (
If the communication quality drops below a certain value while communicating using the old channel, the communication quality will be changed to another wireless base station that satisfies the certain communication quality. Prior to switching to a channel (new channel) and communicating, the switching receiving means and the switching transmitting means are switched at a speed that does not affect the communication signal, and the old channel and the new channel are temporarily transmitted and received in parallel. During this time, you can investigate the quality of the new channel and confirm that it is above a certain level.
The switching operation was completed and communications were made only through the new channel. Therefore, instantaneous communication interruptions due to channel switching are no longer caused.

Embodiment FIGS. 1A and 1B show a system configuration for explaining an embodiment of the present invention.

In FIG. 1A, 10 is a general telephone network, and 70 is a gateway exchange for connecting the telephone network 10 and a wireless system. 20 is a wireless system control 1III device;
It controls multiple radio base stations 30 and many mobile radio devices in order to set up and release radio lines and perform channel switching in conjunction with zone migration. Wireless base stations 30-1 and 30-2
When each radio base station 30-1 and 30-2 receives a transmission wave from a mobile radio, the communication control unit 21 that controls the station, the ID identification unit 24 that identifies the identification number of the mobile radio The S/N monitoring unit 22 monitors the communication quality, and the communication control unit 21 controls the communication quality. F5A base station 30-1.
30-2 and a switch u23 necessary for communication system switching to establish a connection with the gateway exchange 70.

FIG. 1B shows a mobile radio device 50 that communicates with each radio base station 30-1, 30-2. The received signal received by the antenna section is Reception Miku 1).

63 and a radio receiving circuit 68 including a receiving section 53, and the output communication signal is inputted to a control section 58 and a telephone section 59. The communication signal output from the telephone unit 59 is applied to a wireless transmission circuit 66 that connects the transmission mixer 61 and the transmission unit 51, and the transmission signal is sent out from the antenna unit and
Received by base station 30.

This mobile vJ radio 50 is equipped with a synthesizer (Noia 5
5-1.55-2.55-3 and 55-4, changeover switch 64-1.64-2, and reception switch that generates signals for switching changeover switches 64-1 and 64-2, respectively. oscillator 65A and transmission switching oscillator 67A
The synthesizers 55-1 to 55-4 and both switching oscillators 65A and 67A are controlled by a control section 58. A reference frequency is supplied from a reference crystal oscillator 71 to each synthesizer 55-1 to 55-4.

The operation will be described when mobile radio 150 switches the speech (communication) channel from communicating with radio base station 30-1 to communicating with radio base station 30-2 as the car moves. In addition, the feature of the present invention, which is that there is no instantaneous interruption due to channel switching, will also be explained.

It is assumed that the mobile radio device 50 is communicating with the radio base station 30-1 using the communication channel CH1 using the synthesizer 55-1.55-3, the radio receiving circuit 68, and the radio transmitting circuit 66. The mobile radio device 50 moves away from the radio base station 30-1 and moves away from the radio base station 30-1, as described in FIG.
Suppose that it approaches -2. Then, as the relative distance between the mobile radio device 50 and the radio base station 30-1 increases,
As the call quality begins to deteriorate, the wireless system m shown in Figure 1A
In the device 20, the S/N monitoring unit 22 detects a deterioration in the quality of the transmission signal from the mobile radio device 50 received by the radio base station 30-1 (that the quality has fallen below level 1). In addition,
Even at level [1, the line is set to exceed the required value. All nearby wireless base stations 30 are requested to measure the quality of the transmitted signal of the mobile wireless device 50.

In response to this request, each radio base station 30 sends the measured value to the radio system control device 20, and also sends the measured value to the radio system control device 20.
The N monitoring unit 22 starts comparison with level L2 of the communication quality standard. As a result of the comparison, if it is confirmed that the measurement result of the radio base station 30-2 has the best value and satisfies the quality standard level 2 or higher, but L2>11, then the mobile radio device 50 , determines that it has moved to the communication zone (Zone 2) of wireless base station 30-2, and decides to switch channels. Then, as a result of investigating available communication channels in zone 2, it is learned that Chitnel CH2 is usable. Therefore, using the currently active downlink communication channel CH1, the mobile radio device 50 is instructed to prepare for transmission and reception on the communication channel CH2 using a picture setting signal.

At the same time, it also instructs the radio base station 30-2 to perform transmission and reception on channel Cl-12.

After issuing these instructions, the radio system control device 20 simultaneously turns on switches SW1 and SW2 of the switch group 23, and also sets the radio base station 30-2 to the same state as the radio base station 30-1. start sending out call signals. It goes without saying that the modulation depths of the modulators of both radio base stations are also the same.

In order to realize the transmission of this control signal, specifically, when the control signal is an analog signal, as shown in Figure 2 (a), low frequency fDo (e.g. about '100Hz> or high frequency fDl, fD2.fI)
3”・fD8 (for example, from 3.8KH2 to 0.1KH
8 waves up to 4.5 KHz at 2 intervals) are used.

When there are many items to be controlled, that is, many control data, the control frequency f. The wave number of O""08 may be further increased, or a subcarrier format may be adopted. At this time, more control data can be transmitted by, for example, applying frequency modulation or amplitude modulation to one or more waves of fDO'' fD8.

Furthermore, when a digital data signal is used as a control signal, it is also possible to digitally encode the audio signal and time-division multiplex the two to be transmitted.
Shown in Figure (b). FIG. 2(b) shows an example of a case where an audio signal is digitized by a digital encoding circuit 91, and the audio signal is multiplexed with a data signal by a multiplex conversion circuit 92, and then applied to the modulation circuit of the transmitter 31.

FIG. 3 shows a timing chart of the system shown in FIG. 1 before and after channel switching.

In FIG. 3, a wireless base station 30-1 and a mobile wireless device 50
The quality of channel CH1 used between
The S/N monitoring unit 22 of the radio system control device 20 detects that the S/N has decreased to
Using channel CH1, the mobile radio P35
Instruct to 0.

Therefore, the control unit 58 of the mobile radio device 50 uses only the synthesizer 55-1 to receive the waves transmitted by the radio base station 30-1 by channel CH1, and the synthesizer 55-2 also operate, wireless base station 3
The synthesizer 55-2 is made to generate a frequency that makes it possible to receive the transmission wave of the channel CH2 transmitted from the channel CH2.

Channel CH being transmitted from radio base station 30-1
When a transmission wave on channel CH2 is emitted from radio base station 30-2 due to the quality deterioration of I, mobile radio 150 activates reception switching oscillator 65A to repeatedly switch changeover switch 64-1. . At the same time, while only the synthesizer 55-3 was operating and transmitting to the radio base station 30-1 using channel CH1, the synthesizer 55-4 is also operated and the radio base station E
30-2 to a state where it can transmit on channel CH2. The outputs of synthesizers 55-3 and 55-4 used for this transmission are also repeatedly switched by a signal from transmission switching oscillator 67A by changeover switch 64-2.

This switching transmission/reception period in which channels CH1 and CH2 are transmitted and received in parallel continues until the radio system control device 20 confirms that the channel CH2 and the quality of the same channel are at a certain level of 2 or higher. is channel CH
1 is opened, and communication between radio base station 30-2 and mobile radio 150 continues without momentary interruption only through channel CH2.

The switching frequency f1 of the changeover switch 64-1 or 61-2 during this switching transmission/reception period may be logically set to any value as long as the conditions described below are satisfied, but the effect of the present invention is not achieved. However, in the case of other conditions, for example, it is set to be more than twice the R high frequency included in the signal. This will be explained in detail below.

The optimum value of the switching frequency is determined by considering the following conditions.

(1) Modulation format of the signal to be transmitted (2) Signal frequency band to be transmitted (3) Control frequency band to be transmitted (4) Band characteristics of the receiving section, especially the band characteristics of the intermediate frequency amplification section (5) Switching (6) Response characteristics of the frequency synthesizer (7) Carrier frequency and number of channels used in the system (8) Radio wave propagation characteristics of the transmission path (9) From the radio system control device 20 to the radio base station 30-1 For example, (1) is the difference between the transmission time of the signal from the mobile radio 0t50 to the mobile radio 0t50 and the transmission time of the signal from the radio system control device 20 to the mobile radio 50 via the radio base station 30-2. , 0.3 to 3.0 KHz when (2) is an audio signal, and 0.3 KHz when using an out-of-band control signal shown in FIG. 2 (a>) as (3).
Hz or less (foo> or 3.8 to 4.5KHz (f, 1
．． f,2・f,8) and f,;=ru.

As for the characteristics (4), the passband width is 16KHz (or 8KH2), and as the characteristics (5), the response characteristics of the synthesizer in (6) are good and the output waveform is good. Therefore, it is desired that the synthesizer used has an extremely rapid response characteristic due to the input of the switching oscillator (5). (7) to (9) are items to be considered from the system design perspective, but in the car phone system described as an embodiment of the present invention, (7) is 900
MHz, 600 channels (or 1200 channels) (8) is known in many documents, and (9) is 0.0
It is about 3 msec. Therefore, the switching frequency f is selected to be approximately 10 to 12 KHz (or 5 to 7 KH2).

In addition, channel CH1 and channel CH2 due to switching
The time occupancy rate with is not necessarily 50% or 50%, but the ratio of m:n, that is, m/ (m+n)X10
Even if it is set to an arbitrary value such as 0% or n/(m+n)x100%, the effects of the present invention can be similarly exhibited. This is particularly because the reception power of the transmission wave from the radio base station 30-2 to the mobile radio device 50 is usually higher than the reception power from the radio base station 30-1, and the time required for reception of the former is higher. This is more effective in reducing the target occupancy rate than the latter and reducing the receiving input loss of the latter.

In addition, as shown in Figure 2 (b), if the city signals and control signals are digitized, the switching frequency is
It is appropriate to use a higher frequency, 20KH2~3
A value of about 0KI-12 may be sufficient.

Also, the channel CH1 seen from the input section of the reception mixer 63
and the carrier wave frequencies of channel CH2 are ω1 and ω2, and the output frequencies of synthesizers 55-1 and 55-2 are ω, 1 . When ω is 2, the wireless base station 30-
The frequency of the carrier wave at the output of the intermediate frequency amplifier included in the receive mixer 63 from 1 and 30-2 is Ω1=ω1−ωLl (,1)Ω2, respectively.
=ω2-ω[2(2) That is, by the operation of the changeover switch 64-1, the signal wave having a carrier frequency of Ω1=ω1-ω, 1 and the signal wave having an intermediate frequency of Ω2""2-L2 are sent to the receiving section 53 as an intermediate frequency. A signal wave having a carrier frequency of is input to the intersection n. And (1) and (2) are Ω1 → Ω2
The relationship is as shown in (3). Such a signal is amplified in the receiving section and then demodulated in the demodulation circuit, but 2
If there is a frequency difference between the two intermediate frequencies ω1-ω,1 and ω2-ω,2, distortion noise may or may not occur in the demodulated output signal. In other words, in the case of frequency modulation or phase modulation, if there is no frequency difference, no distortion noise will occur, but if there is a frequency difference, the frequency difference (beat frequency) or the same component as the signal frequency will occur. will occur, and will not occur if it is not included.

On the other hand, in the case of amplitude modulation, the frequency difference is constant and no distortion noise occurs. However, even in the case of bow width modulation, if an intermediate frequency amplifier or the like has nonlinear characteristics, nonlinear distortion will occur due to harmonics, and it is necessary to use an amplifier with good linearity.

This phenomenon will be explained theoretically.

First, a case where an angle modulated wave is used will be explained.

A data or audio signal (for signals in analog or digital format) can be expressed as follows.

The control signal that exists outside the band is (4') where ai is the amplitude, ωi is the angular frequency of the signal,
ai represents the phase when 1=0. m.

n represents a positive integer.

Next, the case of frequency modulation will be explained, but the present invention is similarly applicable to phase modulation. When the carrier wave is frequency-modulated using equation (4) or equations (4> and (4')), the resulting modulated wave is 1-10 sin f (ω0μ(t))dt-]□5
ln(ωt+5(t)><5> or I−I□ sin f (ω10μ(1)10μ,,(t)
)dt-I□5in(ω↑15(t)+5o(t))(
5′) However, S (t) −, Y, m1sin (!Jitm・−
a・/ω, (i=1.2.3...n) because it is in the cylinder (
Here, ai = O (i = 1.2.3...n). This results in 5(1)+5o(t) representing the general form of the transmission signal.

Now, using equation (5) or (5'), the signals transmitted from the radio base stations 30-1 and 30-2 are input to the reception mixer 63 via the antenna of the mobile radio 13150, and the local oscillation When mixed with the output (in the case of FIG. 1B, synthesizer 55-1 or 55-2), the receiver 5
The input of 3 can be expressed as in the following equation using the same symbols as in equations (1) and (2). (However, the changeover switch 64-1 is in a stopped state).

11 = I01Sin (Ω1 = 15 (1)) or 12 = 102S! n (Ω2↑10S□ (t)+5
o(t)> (7) Next, assume that the changeover switch 64-1 starts a switching operation. Also, only the audio signal (S(t)) is sent from the radio base station 30-1, and the superimposed signal of audio and control is sent from the radio base station 30-2 (s(t)+
s. (t)) is sent, and as an input to the receiving unit 53 of the mobile radio 50, xsin (Ω1j+5(1)) The angular frequency, n, was a positive odd number, and the switching times for the two input waves were equally spaced.

When formula (8) is transformed, it becomes as follows.

I= Iol (sin (Ωl t+5(t) )+
2-yr-1 [cos ((C1-p) 15(1)
)−cos((Ω1+p)t+5(t))]+2(3π
) [C05((Ωl −3p) t+5(t) )
−cos ((Ω1+3p)t+5(t))] 12 (5π)[C03((Ωl −5p) t+
5(t) ) −cos ((Ω1+5p)t+5(
t))] ten......]
+ 1021'sln (Ω2t+5(t)+5c(t
)) +2・π [cos((C2-p)t +5(t)+5C(1)) -cos((Ω2+p)t+5(t) 15C(t))
]+2(3π) -1[CO3((C2-3p) 15(1)+5o(t)) -cos((Ω2+3p)t+5(t) +5c(1)
Moon+2(5π) −1[cos ((C25p)t+5
(t)+5o(t)) −cos((C2+5p) j +5(t)±s.(1))] −・・・・・・
] (8') Here, (8') shows that it is a combination of many carrier waves, and if it is demodulated after being amplified by an intermediate frequency amplifier, it will generally result in distortion noise due to cross modulation (interference disturbance). may occur.

In addition, the input wave amplitude 101 and IO2 expressed by equation (8)
are not necessarily the same amplitude, and when the switching time occupancy rates are equal (in the case of 50% duty), the wireless base station 31-2 is closer than the wireless base station 31-1, so normally is I. 2 is more human. If the magnitudes of IOI and 102 are different, and the modulation signals differ depending on the radio base station, as expressed by equations (6) and (7), then in the cross-modulation diagram, for the latter, This problem can be solved by providing an amplitude limiting circuit at the output section of the radio receiving circuit 68 so that I01''I02=I. However, this amplitude limiting circuit is not necessarily necessary and can be omitted if the two carrier wave angular frequencies can be made to be completely the same frequency using a phase synchronization circuit or the like.

Next, regarding cross-modulation caused by combining many carrier waves as shown in equation (8'), distortion noise is removed by the following method.

That is, there is a method of increasing the switching speed (period) of the changeover switch 64-1 to drive it out of the bandpass characteristic of the intermediate frequency amplifier. However, as already mentioned, in many cases where the switching frequency is set to be twice or more the highest frequency of the signal, there is no need to make it any faster. By increasing the speed, n on the right side of equation (8) = 1.3
．． As can be seen from equation (8'), the term 5... can be ignored in the intermediate frequency amplification stage, and the term (8
) can be expressed as follows.

l0=I(sin<Ω1t+5(t))+sin (
Ω2t+5(t)+5c(t))) Equation (9) is modified to be expressed as the following equation.

xsin (Ω, t + 5 (t) + ψ (t)) where ψ (t) = tan” (sin ((Ω −C1>
1+S, (t) ) x [1+cos((02-Ωi)t +s (t) ) ] −1) Equations (10) and (11) are transformed and expressed as the following equation.

10 = 2 I [cos((C2-01)t/2)+
5o(t)/2] xsin[((Ω2+01)t/2) +5(t)+s. (1)/2'' (10M In equation (10'), the amplitude change, cos((Ω2-01)t/2+5C(t)/2), becomes O and its frequency becomes the same as the signal frequency, Noise may be mixed into the demodulated signal.

To prevent this from happening, it is necessary that Ω2-Ω1=O2Ω1=Ω2-Ω Is (t)/21<π/2 (12'). Substituting equation (12) into equation (10'), A=2 I C03(Sc(t) /2>xsin(
Ω1 t+5(t)+5o(t)/2>From equation (13), the output of the frequency discrimination circuit (output of the radio receiving circuit 68) is
It is expressed by the following formula.

E=d/dt (S(t)+5o(t)/2)-μ(1
)+μC(t)/2 (14) Here, μ
(1) and μ. (1) is respectively (4) Equation 21'3
and (4').

Note that equation (12') is always satisfied in normal mobile communication systems and is not a particularly limiting condition.

It applies deep modulation to the main audio signal compared to the control signal, and shallow modulation to the control signal.In recent years, the depth of modulation added to the audio has also changed to the equivalent tone (1KH2).
This is because the signal is as shallow as 3.5 radians (if the carrier spacing is 25+"Z, or if the carrier spacing is 12.degree. 5KH7, it will be roughly 1.75 radians).

From the above, it has been clarified that equations (12) and (12') are sufficient conditions for no distortion in the case of frequency modulation. However, this condition is a sufficient condition, not a necessary condition. That is, even if equation (12) is not satisfied, the no-distortion condition may be obtained, but this will be explained in detail later.

Now, return to equation (8) and substitute equation (12). V
That is, assuming that two carrier waves having completely the same frequency enter the mobile radio device 50, equation (8) can be expressed as follows.

x sin (Ωt + 5 (t)) sin (Ω = 15 (t) + 5 o (t)) (8”) Here, 5 o (t) = 0 In other words, no control signal is applied during switching operation (however, , this is a slight system restriction and 1q), then the equation (8'') becomes as shown below.

+1 (1-Σ4 (πn)-1sinnpt) ]x
sin(Ωt+5(t)) (8'''>(8''') The part in [ ] on the right side of the equation represents the amplitude change, but this can be removed by the amplitude control circuit placed before the frequency discrimination circuit. Especially when I = I, the formula (8'') becomes very simple, and 1=21o1stnΩ(t+5(t)).Therefore, in this case, the state remains unchanged by 1 from before the switching operation. Indicates that reception is possible.

The above shows that it does not depend on the switching frequency at all. Therefore, it has become clear that if the frequencies of the two carrier waves are completely equal, the switching frequency of the changeover switch 64-1 shown in FIG. 1B may be arbitrarily selected. However, in an actual system, the above conditions may break down, and for safety reasons, the switching frequency should be set to a higher value, whichever is twice the highest frequency of the signal frequencies or higher than the transmission band frequency width of the intermediate frequency amplification section. Frequency is often selected.

Next, a technically possible method will be described when the equation (12) indicating the no-distortion condition is not satisfied. (1
IAM=2 I [C03((Ω2-01)t/2)+S. (t)/S out of 2. Since (t)/2 is a very small value and can be ignored, the above equation can be expressed approximately as follows.

I' AM=2 I C05 ((Ω2-01)t/2)
The possibility of noise being mixed into the demodulation section included in the reception section 53 of the mobile radio device 50 is determined by the COS (
This is the case when Ω2-Ω1)t/2 has the same frequency component as the signal frequency. In order to avoid this, (Ω2-Ω1)/2>ωi/2 or (Ω2-Ω1)/2<ω1/2. However, ωi is expressed by (4) or (4'
) represents the signal frequency given by the formula (i=1.2.・
..., n).

In other words, it can be seen that the beat frequency represented by Ω2 - Ω1 should be controlled so that it always exists above or below the signal frequency so that it does not go out of that range.

However, since the above-mentioned AM component has a rectangular waveform due to the amplitude limiting circuit, the noise also has a pulse-like waveform, and it is necessary to pay attention to harmonics. Technically, to do this, the transmitter 31- of the wireless base station 30-1, 30-2
This is achieved by increasing the frequency stability of the reference crystal excavator, which determines the stability of the carrier frequency of 1°31-2.

For example, in the example of the car telephone system described later, the stability of the reference crystal generator installed at the base station is currently 0.5.
Since it is about 1 ppm (0.5 to 1 x 1 O-6), the frequency fluctuation of the carrier wave is 1 x 10 x 900 MH2 =
It is 900112. In this case, noise is just mixed into the audio signal band.

However, due to advances in technology, 0.01ppm is possible.
-, then 1 x 1O-8x 900MH
z=9 fiz, and even if there is a high frequency noise, the possibility that its large energy will mix into the signal band is reduced. Alternatively, in a wireless system using a carrier wave frequency of 9 MHz, a carrier wave fluctuation of '+ppm will not cause noise mixing even with the current technology.

The case where the mobile radio device 50 receives is explained above, but the case where the mobile radio device 50 transmits will be explained below. In this case, there is no problem with mobile station reception.

In FIG. 1B, the wireless signals switched by the changeover switch 64-2 are, for example, wireless channels CH1 and CH20.
0 are mutually switched, but the receiving side is the wireless base station 30.
-1 (CHl) or wireless base station 30-2 (CH2
This is because there is no cross-modulation problem when the signals are received separately at 00> and mixed as in the case of reception on the mobile radio side. However, as is clear from equation 8'), components of the carrier angular frequency (Ω±rl) exist as sidebands, and these are emitted into space and are used for communication in other channels or other systems. Band 1 on the transmitting output section to prevent interference! It is necessary to provide an i-filter for filtering.

For this purpose, it is necessary to spread the equation (Ω±np) outside the frequencies of all channels transmitted by the mobile radio 50 as a switching frequency, and the car telephone system shown in FIGS. 1A and 1B used in the example Then, it is necessary to set p/(2π)>15MHz.

As is clear from the above description, the operation of the present invention is to predict the frequency shift after switching to a new communication channel by measuring the transmission frequency of the mobile radio device 50 at the radio base station 30, and to predict the frequency shift after switching to a new communication channel. By setting and using the transmission channel of the wireless base station that communicates after channel switching at an appropriate frequency, the system eliminates noise caused by call interruptions and cross-modulation that occur due to channel switching.

Next, 1M combination of amplitude modulation will be explained.

In this case as well, when the carrier wave (angular frequency ω) is amplitude modulated using equations (4) and (4'), 1 = I (1+μ(t)) sinωt (1
5> or 11=IO(10μ(1)10μ.(t)) Sin
ωt (15') where I) is the size of the channel width of the carrier wave, and t represents the time 'j'. Also, in order to avoid overmodulation,
(t) l<1 (16) 1μ. (t)
l<1 (17) 1μ (1) 10μ (t
)1≦1 (18). Wireless base station 30-
When transmitted from 1 and 30-2 to mobile radio Bi 50, the radio signal waves are expressed by the following equations at the antenna input section of mobile radio 50.

A1=11 (1+μ(1)) Slnω1 tA
=12 (1+μ(1) 10u.(t) ) S! nω2 t However, rl and I2 are the reception mobile radio equipment 50 of the signal waves transmitted from the radio base stations 30-1 and 30-2, respectively.
When the local oscillation output can be controlled intermittently by switching the selector switch 64-1 (FIG. 1B), the input signal to the receiving section 53 is ``11o=11 (1+μ(t)) (1+Σ4 (yrn) sin npt)si
nω1tI20=I2 (1+μ([) +!lc
(j) )-1・ (1-Σ4 (7rrl) sin r'1pi)
S! nω2 jHere, if we assume that hM is close enough to consider ω1 and ω2 to be the same radio channel, then (
2), the signal shown in equation (22) can be amplified by the intermediate frequency amplifier. Therefore, if it is amplified to an appropriate level by the intermediate frequency amplifier and then applied to the demodulation circuit (amplitude detector), , the desired low frequency output will be obtained, but
The no-distortion condition will be explained in the case where p is a signal component such that ω1=ω2=ω, that is, two carrier frequencies are the same.

In this case, equations (21) and (22> are regarded as one carrier wave, and are expressed by the following equation.

1 ”” I 10+120 = [11(1+μ(t)> (1+Σ4 (yrn) −1 sin pt '1 where, p>2ω■ (24) If ω1 is the highest frequency at the back of the signal component, demodulation after AM detection The output is
p by a low pass filter.

As long as the distortion component of p−ωi can be removed, e = k (
2μ(t) +u is )) (25>C is 17. However, k is a constant. Also, the presence of nonlinearity in the intermediate frequency amplifier is also expressed in equation (23), which is expressed in one-wave amplification. There is no need to worry at all.

Therefore, the audio signal μ[1) and the control signal μ. (t) uses different frequency components and can be extracted separately using a bandpass filter.

Next, the case where ω1≠ω2 will be explained. In this case, ω1
→It is necessary to select an amplifier with good linearity so that it is amplified within the same intermediate frequency band at ω2. The following description will be made assuming that there is no effect of non-linearity. Then, an AM modulated wave expressed by the following equation is input to the AM detection input.

""IOI+120 p>2ωI, the output after AM detection is e□ =k ((11+12)μ(1)+I2μC
(t)) (27> is obtained. However, k is a constant. Therefore, in this case as well, both the audio signal and the control signal are reproduced without distortion.

Hereinafter, a specific system configuration method that satisfies equation (12) will be explained using NTT's car telephone system as an example.

FIG. 9 shows the configuration of a conventional mobile radio device. Of this configuration, the transmitter and receiver are closely related to the present invention, and detailed circuit configurations of these are shown in FIGS. 10 and 11, respectively. Among these figures, the synthesizer [herein Fig. 9, Fig. 10, Fig.]]
The 12th map of Kyou Ayohi No. 1 is shown by Nippon Telegraph and Telephone Public Corporation.
Research and practical application report published by Telecommunications Research Institute, July 22, 1977 26. No. 7, p. 198, p. 1996.

1997 and 1995 with explanations.

In these figures, BPF, LPF, and HPF are bandpass filter, lowpass filter, and bypass filter, respectively, and VCO is a voltage controlled oscillator, x5
．． x9 is a multiplier, 1/K.

1/N is a frequency divider, and MIX is a mixer.

Now, the mobile radio 50 uses the f! The frequencies of the carrier wave and the receiving local oscillation output are centrally determined by a reference crystal (TCXO) included in the synthesizer circuit shown in FIG. If the oscillation frequency according to the design value is output, the transmission frequency from the mobile radio device 50 will be completely determined by the system design value. N> or other types of circuits such as mixing circuits (MIX) are included, but these do not have the function of multiplying or dividing a predetermined frequency, or mixing other frequency inputs. However, it does not have the function of changing the frequency by a minute amount.

In contrast, only the reference crystal oscillator has this functionality.

However, in the present invention, this function may bring some inconvenience, but on the other hand, this property can be utilized to give specificity to the present invention.

Now, the reference crystal oscillator (TCXO>
With the invention, the conditions required for mobile radio equipment become very simple and simple, with the output horn frequency completely filling the design value.

However, in reality, the reference crystal oscillator (TCX
Depending on the state at the time of manufacture, the output frequency of O) may not completely satisfy the design value, and the oscillation frequency may change over time, albeit by a small amount, due to surrounding environmental conditions or changes over time. . This change is quite slow and can be considered to be almost constant within a few minutes or tens of minutes when a car phone is used for one call. Therefore, if this error is Δω (angular frequency), the relationship between the design value ω0 and the actual oscillation angular frequency ω should be maintained as ω0~ω=Δω (28) within a certain period of time. become.

In other words, it can be regarded as constant while channel switching is actually being performed using this mobile radio device. Therefore, if the i-channel number used by the mobile radio device and the frequency of the radio carrier wave transmitted from the mobile radio device are measured at the radio base station 30-1 or 30-2, the values can be determined by the system design value and the i-channel number used by the mobile radio device. By determining the difference (8 f) from the frequency of the mobile radio, the frequency deviation of the quasi-crystal oscillator of the mobile radio device can be uniquely determined.

Therefore, the radio base station 30d15 or the radio system control device 20 prepares a table, and in the table, the difference between the channel number and the radio carrier frequency, 8 f, and the reference crystal oscillator built in the mobile radio device 50 are recorded. frequency shift (
Δfo) can be easily obtained. Same U
), the mobile radio sets the local oscillation frequency currently in use in the radio receiving circuit 68 of the mobile radio 50, changes the frequency of the radio carrier wave transmitted from the radio [150, and changes the frequency of the radio carrier wave transmitted from the mobile radio 50. It is also easy to find the frequency deviation (8f, 2) from the design value of the local oscillation frequency used in the receiving section.

Therefore, the angular frequencies of the radio carrier waves transmitted from the radio base stations 30-1 and 30-2 are set to ω1. ω2
Then, the respective intermediate angular frequencies are Ω1-")1-")Ll・Ω2="2"12, and if the relationship Ω1=Ω2 (30) holds, then 12) It means that the exact same conditions as in the formula are satisfied, and then 630 and move! The angular frequency ω1J'3 of the radio carrier wave being transmitted to the II radio 50 having the Birdau configuration and the angular frequency ω of the transmission wave from the mobile radio 50.

is reported to the wireless system control device 20. Wireless system control device 20
Now, from ω□, the deviation from the design value of the local oscillation angular frequency used in the radio receiving circuit 68 in the mobile radio device 50 is determined from the call channel numbers before and after the channel switching during the call using the table described above. These are respectively ω[1, Δω,
Set it to 2. Then, using equations (29> and (30)), ω1-"Ll"2-12 Therefore, ω2 ""1 -11"L2 ""1 +"OL2-(1) OLI -t△ ω[2-△ ω[1(31) However, ω and ω are constant OL2 from the system setting δ4
0LI is the expected value.

Equation (31) teaches the following. That is, as the angular frequency of the radio carrier wave to be transmitted from the radio base station 30-2, the local oscillation angular frequency ω determined by the communication channel number is the transmission angular frequency ω1 of the radio base station 30-1,
What is necessary is to add ω or subtract OF2 0L1 , and add or subtract the angular frequency shift of the local oscillator thereto.

In fact, in equation (31), the main operation in the transmitter 31-2 in the wireless base station 30-2 is necessary due to the presence of a circuit that changes the oscillation angular frequency of the reference crystal oscillator circuit by a minute amount. Ru.

A specific known circuit configuration diagram is shown in FIG.

FIG. 13 shows in detail only the reference crystal oscillator of the synthesizer section disposed in the transmitting section 31 of the wireless base station 30, and the other circuits are controlled by the variable angular frequency oscillator 82 according to instructions from the mobile signal. The oscillation angular frequency changes, and this output and the output of the transmitting crystal oscillator 83 are mixed in a mixer 84, and after passing through a filter 85, which is a bandpass filter, the angular frequency is measured in a frequency measuring section 86. . The results of this measurement are transmitted to the reference oscillator control unit 81 and the wireless system control device 20.
If the specified oscillation angular frequency is not obtained, an error signal is further applied to the variable angular frequency oscillator 82.

This operation will be continued until the required oscillation angular frequency is obtained. Here, the frequency measurement accuracy of the frequency measuring section 86 is required to be high, and a crystal oscillator kept at a constant temperature must be used as a reference. mobile radio t150
Now, due to the operation of the changeover switch 64-1 as described above, the output of the reception mixer 63 is changed to the radio base station 30-
The transmission angular frequency from channel CH2 from channel CH2 and the transmission frequency from radio base station 30-2 are exactly the same carrier angular frequency, and since they satisfy the above-mentioned formula (13), demodulation is possible without distortion. becomes.

The system configuration above has been explained with the aim of completely satisfying equation (12), but in reality, as already explained, the undistorted condition of the received signal does not necessarily have to satisfy equation (12). is satisfied. In other words, by simply increasing the frequency stability of the reference crystal oscillator built into the radio base station 30 or mobile radio @ 50 by two orders of magnitude, there is no need to calculate the transmission frequency within the radio system control device 20 as described above. become. Furthermore, the no-distortion condition is also satisfied at the technical level of crystal stability.

Although the explanation has been given using an example in which four synthesizers 55-1 to 55-4 are installed in the mobile radio device 50 shown in FIG. 1B,
Synthesizer 55-1.55-3 as shown in FIG. 4A
A changeover switch 64-1, 64-2 is provided on the input side of the switch, and the output signal of the switching oscillator 65 having the functions of both the receiving switching oscillator 65A and the transmitting oscillator 67A shown in FIGS. 1B and 1C is added. By switching, the number of installed synthesizers can be reduced to one for transmission and one for reception. As roughly shown in FIG. 4B, a difference frequency oscillator 69 generates a frequency that is the difference between the transmitting frequency and the receiving frequency. The output of the synthesizer 55-1 is mixed with the output of the synthesizer 55-1 to obtain the necessary frequency for transmission.In the circuits shown in FIGS. 4A and 4B, a synthesizer with good response characteristics is 55-1.
You need to choose 55-3. In this manner, the radio system control device 20 causes the radio base station 30-2 and the mobile radio device 50 to prepare for communication using the radio channel CH2. Then, in addition to the switch SW2 that had been turned on in the switch group 23 in the wireless system control device 20, the switch SW1 is also turned on, and the wireless base station 30
The call signal is also sent to -2 in parallel.

Next, the method of using the control signal, which plays an important role in channel switching during a call according to the present invention, will be explained.

However, it is assumed that the condition of equation (12) and the condition that the levels of the two input carrier waves at the intermediate frequency amplification stage are equal are satisfied.

Channel CH1°CH from stations 30-1 and 30-2
2 are transmitted as the same call signal, which is switched by the changeover switch 64-1 in the mobile radio@50, and is selectively received. Furthermore, since the changeover switch 64-2 also starts operating, the transmission wave from the mobile radio 1150 also starts to be switched and transmitted.

Here, the route from the radio system control device 20 to the mobile radio device 50 via the radio base station 30-1 and the route from the radio base station 30-1 to the mobile radio device 50 and the radio base station 30-
The delay time difference due to the difference (within 10 KIrt) from the route via No. 2 is at most 0.03 msec or less, and there is no problem with the operation and can be ignored. Further, although the downlink signal from the radio base station 30-1 is only a voice signal, the radio base control unit 58 identifies this signal and sends the signal from the radio base station 30-2 according to instructions from the radio system control device 20. Since it is confirmed that a call signal has been sent using the channel CI "2," the radio transmission circuit 68 is used to use a signal outside the uplink call signal band, and this confirmation item is used for the radio base station 30-1. The communication channel Cl-11 is used to report to the radio system control device 20 via the radio base station 30-1.

When the radio system control device 20 confirms that the downlink communication between the radio base station 30-2 and the mobile radio device 50 is working properly, it instructs the radio base station 30-1 to stop transmission. For the mobile radio device 50, the switching reception by the operation of the switching oscillator 65 is stopped, and the switching switch 64-1 is turned on.
(See Figure I8)
Shown in Figure A.

2, h Next, from the mobile radio device 50, channels Cl-11,c
A case of transmitting to the wireless base station 30-1, 30-2 using H2 will be explained.

In the mobile radio device 50, the reception switching oscillator 65 and the transmission switching oscillator 6
7 are activated, and the changeover switches 64-18 and 6
4-2 is in operation, switching the outputs of the synthesizers 55-1 and 55-2, and the outputs of 55-3 and 55-4, and switching between channels CI-11 and CH2. Figure 1B).

The signals sent to this active communication channel include, in addition to the communication signal, an out-of-band control signal (Fig. 2 (a)).
Status of channel used by mobile radio 50 (channel CH1
When it is received from channel CH2 with = 1, as shown in Fig. 6 (
As shown in a), since switching is started by the operation of the reception switching oscillator 65, the call signal has a pulsed reception waveform.

This waveform can be expressed in the form of the first term on the right side of equation (8), so by making the switching frequency larger than the frequency bandwidth used in the system, the The signal is filtered by a bandpass filter (see FIG. 11) provided in the human part, and only the normal frequency modulation is transmitted from the antenna. Then, the required signals are received without any abnormality among the demodulated audio signals and out-of-band signals and are transferred to the wireless system control device 20.

, :tshi.

2: Reception is possible from the time the switching starts, and no 3:
As in the case of the line base station 30-1, the received waveform is a pulse. However, for the same reason as mentioned above, the required signals are received without any abnormalities in the demodulated audio signals and out-of-area signals, and are transferred to the radio system control device 20.

In the wireless system system tilIl device 20, the wireless base station 30-1
Of the two signals from radio base stations 30-1 and 30-2, the audio signal is mixed with the signals from radio base stations 30-1 and 30-2. Note that when mixing, the signals from the radio base station 30-2 usually have better transmission quality, and may be mixed with an output proportional to the S/N. In addition, when mixing, among the two signals of the route from the mobile radio device 50 to the radio system control device 20 via the radio base station 30-1, the route via the radio base station 30-2, and the signal from the radio base station 30-2, It is confirmed that the signals are from channels CI-11 and CH2 from the mobile radio device 50, respectively, by identification signals sent outside the voice band.

The radio system control device 20 confirms that the channel switching operation is proceeding smoothly during the call, and then sends the message to the mobile radio device 50 via the radio base station 30-2 on the channel CH2.
A command signal is sent to stop communication with the radio base station 30-1 via channel CHI and concentrate on communication with the radio base station 30-2.

In the mobile radio device 50 that has received this control signal, the control unit 5
8 fixes the position of oscillation j*, j-2 of the switching oscillator 65 to the synthesizer 55-4 side.

t・′ As a result, the mobile radio device 50 changes the previous channel CI
-11 to end the communication with the wireless base station 30-1,
As shown in FIG. 6(C) 1, a state is entered in which communication is performed with the radio base station 30-2 using channel CH2. This completes the channel disconnection, and a state in which communication is being performed on the new wireless channel is realized. The uplink channel and downlink channel switching operations described above are performed in parallel and end at approximately the same time.

As is clear from the above description, there is no momentary interruption during channel switching, and noise can be kept to a low level that poses no problem in practical use.

After the various channel switching operations described above are completed, the transmission frequency of each radio station requires specific conditions.

If 7 good or no movement occurs, you will have to start over from the previous movement. In addition, when the movement disorder is large,
The controller 58 also includes an operation for returning to the communication channel before the switching operation, which is stored in the memory section.

78 through 7D are flow charts showing the flow of operation of the system shown in FIG. 1.

Wireless system control device 20. The wireless base station 30-1, 30-2 and the mobile wireless device 50 start operating, and the wireless system control device 2
Switch SW2 of the switch group 23 included in No. 0 is on, and communication is in progress between the wireless base station 30-1 and the mobile wireless device 50. For this communication, channel CH1 instructed by the communication control unit 21 included in the radio system control device 20 is used.
, downlink frequency F1 and uplink frequency f1 are used (S
A reception status report from the mobile radio 150 is issued (3102).
, the S/N monitoring unit 22 of the wireless system control unit U20 receives this.
Then, it is monitored whether the call quality has deteriorated below level L1 (S103). Call quality is level L1
(S103YES), the communication control unit 21 sends the wireless base station 30-1 and the mobile radio device 50 to the wireless base station 30 in the vicinity of the wireless base station 30-1.
3104).

Each of the surrounding wireless base stations 30 (for example, 3O-2) that received the monitor reception instruction monitors and receives the signal of frequency f1 (5105), and sends the result to the S/S of the wireless system control device 20.
It is reported to the N monitoring unit 22 that it is detected that the S call quality is better than a certain standard level L2 and is the best (S1
07YES).

Therefore, the communication control unit 21 determines that the mobile radio device 50 has moved from the zone covered by the radio base station 30-1 to the zone covered by the radio base station 30-2 (3108).
4B), in order to switch to communication with the radio base station 30-2, the radio base station 30-2 searches for an empty channel that can be used (3109), and as a result, the channel C
Determine H2 (3110). The communication control unit 21 uses mobile radio #7! Transmitting unit 51-2 and receiving unit 53- of i50
2 to prepare for communication on channel CH2 (3111).

A communication preparation command for using this channel CH2 is sent to the radio base station 30-2, and is used to prepare for making channel C communication possible, that is, from the control unit 58 to the synthesizer 5
5-26 and 55-4, the frequency e! 1F, instructs to transmit at frequency f2, and the switching oscillator 65 enters switching operation (3115, Fig. 4C).
.

When ready to communicate using channel CH2, mobile radio 150 reports completion of preparation to radio base station 30-2 using channel CH2 (S116).

Upon receiving this report, the wireless base station 30-2 performs step 51.
Radio base station 30- using channel CH2 prepared in step 12
2 confirms that the preparations are complete and issues a report (3117).

- When the line system control device 20 confirms (5118):
The switch SW2 of the switch group 23 is left on, and the switch SW1 is also turned on (S119).

Therefore, the communication control unit 21 included in the radio system control device 20 instructs the radio base station 30-2 to start communication with the mobile radio 1m50 using channel CH2 (S120>.

Upon receiving this communication start command (S121>, the radio base station 30-2 transmits a communication start command using channel C12 (S122).The mobile radio device 50 sends an identification signal for identifying the mobile radio device. The radio base station 30 that received this communication signal confirms the start of communication using channel CH2 using the ID signal 5123>, and transmits a communication signal including the l signal using channel CH2 (5124, FIG. 4D). -2, the monitoring unit 22 that started communication on channel Cl-42 communicates with the mobile non-VA device 50 and the wireless base station 30127.
YES), instructs the radio base stations 30-18 and 30-2 to stop communication using channel CH1 between the radio base station 30-1 and the mobile radio 150 (S128
).

As a result, the radio base station 30-1 turns off communication using channel CHI (3129>.
The radio base station 30-2, which received the command to stop communication by 5130), transfers the command to this channel CHI.
When the mobile radio device 50 receives a communication stop command (S
131), the operation of synthesizers 55-1 and 55-3 is stopped, and the changeover switch 64-1 is switched to
Transfer channel CH1 communication stop report (3133)
.

Radio system control device 2 that received the channel CH1 communication stop report
The communication control unit 21 of No. 0 is a switch SW of the switch group 23.
Leave I on and turn off switch SW2 (S
134).

As a result, the channel switching operation period ends, and with the switch SW1 in the on state, the channel Cl-12, the downlink frequency F2. Using the upstream frequency f2, the mobile radio device 50 can continue communication with the radio base station 30-2 without momentary disconnection or noise mixing (S135).

In the above explanation, the operation was explained under the condition that the output of the intermediate frequency amplification stage included in the reception mixer 63 is equal between the two radio base station three-frequency amplification stages.

A detailed explanation of the present invention will be given in the case where only the condition of equation (12) is used, and the clever condition that the two input levels are equal is removed.

In this case, as already explained, since the control signal S included in the second term on the right side of equation (8'') cannot be inserted as (t)'4, the system will take the following measures. That is, If the IO (identification number) and communication channel number transmitted from the wireless base M30-2 cannot be sent using the lil control signal during the already explained channel switching operation during a call, the mobile radio 50 side An alternative method is to apply 1, t 5 s to the selector switch 64 internally stored in the mobile radio 50.
-1 starts the switching operation at a duty cycle of 50%, the S/N deteriorates by 6 dB if the received wave is only from the radio base station 30-1. Next, the wireless base station 30
If a signal is sent from -2 through the radio channel (CH2) according to the instructions from the radio system control device 20, the S/N will be improved by at least 6 dB for the reason described above. This state is shown in FIG. 5B. This is measured by the reception quality measurement section, reported to the control section, and this information is transmitted from the radio transmission circuit 66 of the mobile radio device 50 to the radio system control device 2 via the radio base station 30-1.
0, channel switching during a call can be performed by the same operation as described above.

Furthermore, even if the condition of equation (12) is not satisfied, if the frequency stability of the radio carrier included in the system is sufficiently high, and the stability of the reference crystal oscillator that determines the stability is sufficiently high, An example of a simple and economical system configuration that can perform the same functions as those described above is shown and explained in FIG. 1C.

FIG. 3B is a timing chart similar to FIG. 3A to illustrate the operation of the system in this case.

FIGS. 1B and 1 show the circuit configuration of the mobile radio device 50B.
The difference in Figure C is that the reception switching oscillator 65 is replaced by a reception switching controller 65B, the transmission switching oscillator 67 is replaced by a transmission switching controller 67B, and the control unit 58B performs slightly different control from the control unit 58. This is what happened.

The process up to the activation of channel CH2 by the radio base station 30-2 as explained in FIG. 3A is exactly the same, and this channel
2. Upon receiving the start-up instruction, the mobile wireless device 50 as shown in FIG. 1C completes this channel switching preparation operation.
Both channels CH1 and CH2 from the wireless base stations 30-1 and 30-2 are transmitted to the wireless receiving circuit 68 of the mobile wireless device 50 using the same communication signal. 64-2 is still a synthesizer 55-
1 and 55-3, it is communicating with the radio base station 30-1 through channel CH1. mobile radio 15
0B indicates that the preparation for switching to channel CH2 is completed by using the wireless transmission circuit 68 and using the out-of-band of the uplink communication signal.
This confirmation item is reported to the radio system control device 20 via the radio base station 30-1 using the communication channel CH1 currently in use for the radio base station 30-1.

In response to this report, the radio system control device 20 instructs the radio base station 30-1 to stop transmitting and receiving data from the mobile radio device 50.
For B, by the operation of the reception switching controller 65B,
Stop reception of channel Ct (1) and switch 64
-1 (FIG. 1C) is fixed in a state connected to the synthesizer 55-2 side, and the transmission of channel CH1 is stopped by the operation of the transmission switching controller 67[3, and the changeover switch 64
-2 is connected to the synthesizer 55-4 and fixed.

Thus, after the switching preparation period of mobile radio 50B, communication via channel CH2 is continued with radio base station 30-2.

In FIG. 1C, synthesizers 55-1 to 55-4
4A and 4B, it is clear that the number can be reduced to two or one, as shown in FIGS. 4A and 4B.

In the simple channel switching method described above, although some uncertainty remains in confirming the switching operation of the base station transmission wave, the mobile radio 50B uses the transmission wave of the mobile radio 50B to transfer the transmission wave of the station 30-2 to the mobile radio 50B. It is also possible to estimate the electric field value at the time of reception, and it is thought that it will be widely used to provide an economical and uninterrupted channel switching method. Further, by confirming that the reception quality after switching is level 2 or higher, it is possible to prevent failures such as malfunctions.

[Effects of the Invention] As is clear from the above explanation, by applying the present invention to a mobile communication system that uses a small zone configuration, it is possible to eliminate the temporary interruption of communication when changing zones during communication, as in conventional systems. Although this is not a big problem in the case of telephone signals, it has become a problem in facsimile signals and data signals due to image quality deterioration and errors in the first and second verse signals. communication quality.

[Brief explanation of drawings]

1A and 1B are system configuration diagrams showing one embodiment of the present invention; FIG. 1C is a system configuration diagram showing another embodiment of the mobile radio device shown in FIG. 1B; FIG. 2(a) and (b) is a spectrum diagram and a circuit configuration diagram for explaining a configuration example of a control signal used in the present invention, and FIG. 3A is a timing diagram and a circuit diagram for explaining the operation of the system shown in FIGS. 1A and 1B. Figure 3B is a timing/chill rate, signal status diagram, Figure 7A, Figure 7B, Figure 7C, and Figure 7D to explain the operation of the system shown in Figures 1A and 1C. The figure is a flow chart showing the flow of operation of the system shown in Figure 1. Figure 8 is a conceptual diagram of the system configuration to explain an example of a conventional system. Figure 9 is a conventional mobile radio system. 10 is a detailed circuit diagram of the transmitting section and power amplifying section among the components shown in FIG. 9, and FIG. 11 is a detailed circuit diagram of the receiving section among the components shown in FIG. 9. (Figure 12 is a detailed circuit configuration diagram of the synthesizer section, which includes the components shown in Figure 9. Figure 13 is a diagram of the reference crystal oscillator of the synthesizer section 1.)
This is a detailed circuit configuration diagram. 210...Telephone network 11...Exchange '1 button 2...Radio line control station 13A-D...Wireless base station name. A~. , J->15-Mobile radio 16A-D
...Transmission path 20...Radio system control device 21...
Communication control unit 22...S/N monitoring unit 23...Switch group 30-1.30-2...Radio base station 31-1.31-2...Transmission unit 33-1.33-2 ... Receiving section 50... Mobile radio device 51... Transmitting section 53...
- Receiving units 55-1 to 55-4...Synthesizer 58...Control unit 59...Telephone unit 61...Transmission mixer 63...Reception mixer 64-1, 64-2...
Changeover switch 65...Switching oscillator 65A...Reception switching oscillator 65B...Reception switching 11 controller 66...Radio transmission circuit 67A...Transmission switching oscillator 67B...Transmission switching control Device 68... Radio reception circuit 69... Difference frequency oscillator 70... Frequency mixer 71... Reference crystal oscillator 81... Oscillator control section 82... Variable color frequency oscillator 83... Transmission crystal Starting (Tatsuki 84...Mixer 85...δ/Gowaki 86
...Frequency measurement section

Claims (28)

[Claims] (1) between each radio base station that covers a plurality of zones and constitutes a service area, and each mobile radio that moves across the plurality of zones and communicates with the radio base station; In the method of controlling the radio base station and the mobile radio so that the communication quality is always above a certain value, the mobile radio is configured to alternately switch between a first radio channel and a second radio channel for transmission and reception. By providing channel switching means to switch between channels, when the communication quality deteriorates below a certain transmission quality due to movement during communication using the first radio channel with an opposing radio base station, Prior to communicating using the second radio channel with another radio base station that can obtain communication quality, the channel switching is performed between the first radio channel and the second radio channel. providing a switching transmission/reception period in which communication is alternately switched by means, and confirming that the communication quality through the second channel is above a certain value;
A wireless channel switching method for mobile communication, characterized in that communication is continued only through the second wireless channel. (2) When the mobile radio device receives the second radio channel, the frequency of the carrier wave of the second radio channel at the output of the intermediate frequency amplifier of the receiving means included in the mobile radio device is 2. The wireless channel switching method for mobile communications according to claim 1, wherein the frequency is set to be substantially equal to the frequency of the carrier wave of the first wireless channel. (3) In the output of the receiving means included in the mobile radio during the switching transmission/reception period, the signal components of the first and second radio channels are made to be substantially equal. The wireless channel switching method for mobile communication described above. (4) The signal components of the first and second radio channels are limited to a certain level in order to make the signal components of the first and second radio channels substantially equal. 3. The wireless channel switching method for mobile communication according to item 3. (5) In order to make the signal components of the first and second radio channels substantially equal, the reception period of the smaller one of the signal components of the first and second radio channel is lengthened, and the 4. The wireless channel switching method for mobile communication according to claim 3, wherein the switching period in the switching transmission/reception period is controlled so as to shorten the reception period of the mobile communication. (6) each radio base means each covering a plurality of zones to constitute a service area; each mobile radio means for moving across the plurality of zones and communicating with the radio base means; Radio system control means for controlling the radio base means and the mobile radio means so that the communication quality between the base means and the mobile radio means is always above a certain value. In the channel switching system, the mobile radio means includes a radio reception means capable of selectively receiving many radio channels, a radio transmission means capable of selectively transmitting many radio channels, and a control signal. , for causing the radio receiving means to switch and receive the first downlink radio channel and the second downlink radio channel, and to cause the radio transmitting unit to switch and transmit between the first uplink radio channel and the second uplink radio channel. between the switching means and a radio base station capable of obtaining the best communication quality when the communication quality of the first radio channel consisting of the first uplink and downlink radio channels deteriorates below a certain transmission quality; , prior to communicating using a second radio channel consisting of the second uplink and downlink radio channels,
The switching means is controlled to alternately switch reception and transmission between the first and second radio channels, and when the communication quality of the second radio channel is equal to or higher than a certain value, reception and transmission are performed only through the second radio channel. A wireless channel switching system for mobile communication, comprising: a control means for outputting the control signal to be applied to the switching means to enable transmission. (7) The radio receiving means includes a receiving means including an intermediate frequency amplifier, and the frequency of the carrier wave of the second downlink radio channel in the output of the intermediate frequency amplifier is higher than the carrier wave of the first downlink radio channel during the communication. 7. The wireless channel switching system for mobile communication according to claim 6, further comprising synthesizer means for applying a signal having a frequency that can be set to be substantially equal to the receiving means to the receiving means. (8) When the radio receiving means switches and receives the first and second downlink radio channels, the components of the output signals of the first and second downlink radio channels are made to be substantially equal. 7. The wireless channel switching system for mobile communications according to claim 6, further comprising equalization means for the purpose of the present invention. (9) The wireless channel switching system for mobile communication according to claim 6, wherein the wireless receiving means includes a reception mixer that selectively receives many wireless channels according to the signal from the switching means. . (10) The wireless channel switching system for mobile communication according to claim 6, wherein the wireless transmission means includes a transmission mixer that selectively transmits many wireless channels according to the signal from the switching means. . (11) The switching means includes: a first synthesizer that generates a frequency for receiving the first downlink radio channel under control from the control means; and a first synthesizer that generates a frequency for receiving the first downlink radio channel under control from the control means; a second synthesizer that generates a frequency for receiving the downlink radio channel; a third synthesizer that generates a frequency for transmitting the first uplink radio channel under control from the control means; and the control unit. a fourth synthesizer for generating a frequency for transmitting the second uplink radio channel under control from the means; and a fourth synthesizer for generating a frequency for transmitting the second uplink radio channel; a reception changeover switch means for applying the signal to the reception means; a transmission changeover switch means for receiving the transmission changeover signal to switch the outputs of the third and fourth synthesizers and apply the same to the wireless transmission means; and the control 7. The radio channel switching system for mobile communication according to claim 6, further comprising switching oscillation means for generating the reception switching signal and the transmission switching signal under control of the switching means. (12) The switching means generates a control signal for generating a frequency for receiving the first downlink radio channel, and a control signal for generating a frequency for receiving the second downlink radio channel. a control signal for generating a frequency for receiving the first uplink radio channel; and a control signal for generating a frequency for receiving the second uplink radio channel. transmission control changeover switch means for switching signals; and reception means for receiving the control signal from the reception control changeover switch means and generating a signal to be applied to the radio reception means at a frequency specified by the control signal. a synthesizer; and a transmission synthesizer for receiving the control signal from the transmission control changeover switch means and generating a signal to be applied to the wireless transmission means at a frequency specified by the control signal. A wireless channel switching system for mobile communication according to claim 6. (13) A channel for the switching means to switch between a control signal from the control means for selecting the first wireless channel and a control signal from the control means for selecting the second wireless channel. control changeover switch means; receiving the control signal from the channel control changeover switch means, generating a frequency for receiving the downlink radio channel of the channel designated by the control signal and applying it to the radio reception means; a receiving synthesizer for generating a signal having a frequency difference between an output frequency of the receiving synthesizer and a frequency to be applied to the wireless transmitting means for transmitting the upstream wireless channel of the designated channel; A difference frequency oscillation means; and a frequency mixing means for mixing the output of the reception synthesizer and the output of the difference frequency oscillation means to obtain a signal at a frequency to be applied to the wireless transmission means. A wireless channel switching system for mobile communication according to scope 6. (14) The equalizing means adjusts the signal components of the first and second downlink radio channels to a certain level in order to make the signal components of the first and second downlink radio channels substantially equal. Claim 8 includes a limiter for limiting the
A wireless channel switching system for mobile communication as described in 2. (15) The equalizing means may be configured to adjust a small amount of the signal components of the first and second downlink radio channels in order to substantially equalize the signal components of the first and second downlink radio channels. 9. The wireless channel switching system for mobile communication according to claim 8, wherein the switching period of the switching means is controlled so that the reception period of the main channel is lengthened and the reception period of the main channel is shortened. (16) Provide services covering multiple zones.
Each radio base means constituting an area, each mobile radio means that moves across the plurality of zones and communicates with the radio base means, and the communication quality between the radio base means and the mobile radio means. 2. A wireless channel switching system for mobile communication using a radio system control means for controlling the radio base means and the mobile radio means so that communication quality for monitoring the communication quality when the mobile radio means capable of performing a switching transmission/reception operation capable of transmitting and receiving by alternately switching between two radio channels communicates with the radio base means; monitoring means; identification means for identifying each of the mobile radio means; and upon receiving outputs from the communication quality monitoring means and the identification means, when the communication quality falls below a predetermined value, the mobile radio means selecting another radio base means that provides the best communication quality for the mobile radio means, causing the mobile radio means to perform the switching transmission/reception operation, and outputting a control signal so as to have a period for transmitting and receiving the two radio channels at the same time; 1. A wireless channel switching system for mobile communication, comprising: communication control means. (17) The mobile device according to claim 16, wherein the radio system control means transmits a control signal from the radio base station using a communication signal outside the band in order to send a control signal to the mobile radio means. Wireless channel switching system for body communication. (18) In order for the radio system control means to cause the mobile radio means to perform a switching transmission/reception operation,
17. The wireless channel switching system for mobile communications according to claim 16, further comprising a switch group for transmitting the same communication signal to said wireless base means and said other wireless base means that provides the best speech quality. (19) Provide services covering multiple zones.
The communication quality between each radio base station making up an area and each mobile radio device that moves across the plurality of zones and communicates with the radio base station is always above a certain value. In the method for controlling the radio base station and the mobile radio device, the mobile radio device is provided with a channel switching means for switching between a first radio channel and a second radio channel for transmission and reception. When the communication quality deteriorates below a certain transmission quality due to movement during communication with the radio base station using the first radio channel, another radio base station that can obtain the best communication quality Prior to communicating with a station using the second wireless channel, preparation for switching transmission and reception of switching between the first wireless channel and the second wireless channel using the channel switching means. a period of time is set, and during this preparation period, the frequency of the carrier wave of the second radio channel in the output of the intermediate frequency amplifier of the receiving means included in the mobile radio device becomes the frequency of the carrier wave of the first radio channel during the communication. A wireless channel switching method for mobile communication, characterized in that the channels are set to be substantially equal, the channels are set to be substantially equal, the channels are switched to the second wireless channel, and communication is continued using only the second wireless channel. (20) Provide services covering multiple zones.
Each radio base means constituting an area, each mobile radio means that moves across the plurality of zones and communicates with the radio base means, and communication between the radio base means and the mobile radio means. In a wireless channel switching system for mobile communication using a radio system control means for controlling the radio base means and the mobile radio means so that the quality always exceeds a certain value, the mobile radio means has many In order to selectively receive wireless channels,
a radio receiving means including an intermediate frequency means for obtaining an intermediate frequency from a signal of the radio channel; a radio transmitting means capable of selectively transmitting a number of radio channels; A switching means including a synthesizer means for switching reception from a first downlink radio channel to a second downlink radio channel and causing the radio transmitting means to switch transmission from the first uplink radio channel to a second uplink radio channel; When the communication quality of the first radio channel consisting of the first uplink and downlink radio channels deteriorates below a certain transmission quality, the communication between the first radio channel and the radio base station that can obtain the best communication quality is performed. Prior to communicating using a second wireless channel consisting of two upstream and downstream wireless channels,
By controlling the switching means, the frequency of the carrier wave of the second downlink radio channel in the output of the intermediate frequency means is
The control signal is set to be substantially equal to the frequency of the carrier wave of the first downlink radio channel during the communication, and is applied to the switching means to enable reception and transmission only by the second radio channel. 1. A wireless channel switching system for mobile communication, comprising: a control means for outputting. (21) The movement according to claim 20, wherein the radio reception means includes a reception mixer that selectively receives many radio channels by a signal from the synthesizer means included in the switching means. Wireless channel switching system for body communication. (22) The mobile body according to claim 20, wherein the wireless transmission means includes a transmission mixer that selectively transmits a number of wireless channels using a signal from a synthesizer means included in the switching means. Communication wireless channel switching system. (23) The switching means includes: a first synthesizer that generates a frequency for receiving the first downlink radio channel under control from the control means; and a first synthesizer that generates a frequency for receiving the first downlink radio channel under control from the control means; a second synthesizer that generates a frequency for receiving the downlink radio channel; a third synthesizer that generates a frequency for transmitting the first uplink radio channel under control from the control means; and the control unit. a fourth synthesizer for generating a frequency for transmitting the second uplink radio channel under control from the means; and a fourth synthesizer for generating a frequency for transmitting the second uplink radio channel; a reception changeover switch means for applying the signal to the reception means; a transmission changeover switch means for receiving the transmission changeover signal to switch the outputs of the third and fourth synthesizers and apply the same to the wireless transmission means; and the control 21. The wireless channel switching system for mobile communication according to claim 20, further comprising switching oscillation means for generating the reception switching signal and the transmission switching signal under control of the switching means. (24) The switching means generates a control signal for generating a frequency for receiving the first downlink radio channel, and a control signal for generating a frequency for receiving the second downlink radio channel. a control signal for generating a frequency for receiving the first uplink radio channel; and a control signal for generating a frequency for receiving the second uplink radio channel. transmission control changeover switch means for switching signals; and reception means for receiving the control signal from the reception control changeover switch means and generating a signal to be applied to the radio reception means at a frequency specified by the control signal. a synthesizer; and a transmission synthesizer for receiving the control signal from the transmission control changeover switch means and generating a signal to be applied to the wireless transmission means at a frequency specified by the control signal. A wireless channel switching system for mobile communication according to claim 20. (25) A channel for the switching means to switch between a control signal from the control means for selecting the first wireless channel and a control signal from the control means for selecting the second wireless channel. control changeover switch means for receiving the control signal from the channel control changeover switch means, generating a frequency for receiving the downlink radio channel of the channel designated by the control signal, and applying it to the radio reception means; a receiving synthesizer; and a difference frequency for generating a signal having a difference in frequency between the output frequency of the receiving synthesizer and the frequency to be applied to the radio transmitting means for transmitting the uplink radio channel of the indicated channel. oscillation means; and frequency mixing means for mixing the output of the reception synthesizer and the output of the difference frequency oscillation means to obtain a signal at a frequency to be applied to the wireless transmission means. 21. The wireless channel switching system for mobile communication according to item 20. (26) Provide services that cover multiple zones.
Each radio base means constituting an area, each mobile radio means that moves across the plurality of zones and communicates with the radio base means, and the communication quality between the radio base means and the mobile radio means. In a mobile communication radio channel switching system using a radio system control means for controlling the radio base means and the mobile radio means so that Communication quality monitoring for monitoring the communication quality when the mobile radio means that performs a switching transmission/reception operation capable of transmitting and receiving by switching from one radio channel to another radio channel communicates with the radio base means. means, identification means for identifying each of the mobile radio means, and receiving outputs from the communication quality monitoring means and the identification means to identify the mobile radio means when the communication quality falls below a predetermined value. Selecting another radio base means that provides the best communication quality, causing the mobile radio means to prepare for the switching transmission/reception, and controlling the mobile radio means to switch to the other radio channel after confirming completion of the preparation. 1. A wireless channel switching system for mobile communication, comprising: communication control means for outputting a signal. (27) The mobile device according to claim 26, wherein the radio system control means transmits a control signal from the radio base station using a communication signal outside the band in order to send a control signal to the mobile radio means. Wireless channel switching system for body communication. (28) In order for the radio system control means to cause the mobile radio means to perform a switching transmission/reception operation,
27. The wireless channel switching system for mobile communications according to claim 26, further comprising a switch group for transmitting the same communication signal to said wireless base means and said other wireless base means that provides the best speech quality.